I'm not sure about brewers yeast but the yeast that has been shown to help with IBS-D and IBD in research testing is Saccharomyces Boulardii. I take it, it helps.You can get it seperate or some mulit strain probiotics have it as part of thier formula.

 

These are germs, so, of course, they can help. Try also the germs present on cheese(s), cheese(s) with (a lot of) microbs (Roquefort, Camembert etc..). A little every day can help a lot, if you do not tolerate lactose, take lactAse.edit: maybe should I have written : friendly germs, it was obvious for me.

 

ummm germs?... Sorry, for the sake of being concise and to not get other people confused with the "germs" that get you sick, which include viruses, probiotics are mostly bacteria and to a lesser degree, as in Saccharomyces Boulardii, yeast.